1. Field of the Invention
The present invention relates to a distortion compensation amplification device and a correction method.
2. Description of the Related Art
Recently, digitalized high-efficiency transmission has been frequently adopted in wireless communication. In the case where multi-level phase shift keying is applied to the wireless communication, there is a demand for a technique in which an amplifying characteristic of a transmission power amplifier is linearized to suppress non-linear distortion on the transmission side, such as a base transceiver station, thereby reducing an adjacent channel leak power. A distortion compensation amplification device is one of the devices which compensates for the distortion of the amplifier.
In the direct modulation type distortion compensation amplification device, a carrier leak and an image are generated in the transmission data by an offset of the transmission data in a converter or incomplete amplitude. Therefore, the distortion compensation amplification device includes a correction unit which removes the carrier leak or image generated in the converter. The correction unit feeds back a signal supplied from the converter, calculates a correction value for correcting the offset or amplitude of the transmission data, corrects the transmission data using the calculated correction value, and supplies the corrected transmission data to the subsequent converter. Therefore, the carrier leak and the image are removed in the output of the converter (for example, see Japanese Laid-Open Patent Publication No. 09-83587). There exists a wireless apparatus in which, in order to rapidly end distortion compensation processing, the power of the amplifier is turned off and test data for offset detection is supplied from a control unit to perform offset correction (for example, see Japanese Laid-Open Patent Publication No. 10-65570).
A need arises for a distortion compensation amplification device which can optimally and flexibly calculate the correction value in order to remove the carrier leak and the image, and a correction method.